| Message ID | 1408453449-4243-1-git-send-email-namit@cs.technion.ac.il (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Il 19/08/2014 15:04, Nadav Amit ha scritto: > Commit 5045b46803 added a check that cs.dpl equals cs.rpl during task-switch. > This is a wrong check, and this patch introduces a test in which cs.dpl != > cs.rpl. To do so, it configures tss.cs to be conforming with rpl=3 and dpl=0. > Since the cpl after calling is 3, it does not make any prints in the callee. > > Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> > --- > x86/taskswitch2.c | 23 +++++++++++++++++++++++ > 1 file changed, 23 insertions(+) > > diff --git a/x86/taskswitch2.c b/x86/taskswitch2.c > index 92fc941..1fe833e 100644 > --- a/x86/taskswitch2.c > +++ b/x86/taskswitch2.c > @@ -7,6 +7,7 @@ > > #define MAIN_TSS_SEL (FIRST_SPARE_SEL + 0) > #define VM86_TSS_SEL (FIRST_SPARE_SEL + 8) > +#define CONFORM_CS_SEL (FIRST_SPARE_SEL + 16) > > static volatile int test_count; > static volatile unsigned int test_divider; > @@ -102,6 +103,14 @@ start: > goto start; > } > > +static void user_tss(void) > +{ > +start: > + test_count++; > + asm volatile ("iret"); > + goto start; > +} > + > void test_kernel_mode_int() > { > unsigned int res; > @@ -248,6 +257,19 @@ void test_vm86_switch(void) > report("VM86", 1); > } > > +void test_conforming_switch(void) > +{ > + /* test lcall with conforming segment, cs.dpl != cs.rpl */ > + test_count = 0; > + set_intr_task_gate(0, user_tss); No need to use set_intr_task_gate, since the IDT is not involved here. tss_intr.eip = (u32)user_tss; is enough. I fixed this up and applied the patch. Thanks! Paolo > + > + tss_intr.cs = CONFORM_CS_SEL | 3; > + tss_intr.ds = tss_intr.gs = tss_intr.fs = tss_intr.ss = USER_DS; > + set_gdt_entry(CONFORM_CS_SEL, 0, 0xffffffff, 0x9f, 0xc0); > + asm volatile("lcall $" xstr(TSS_INTR) ", $0xf4f4f4f4"); > + report("lcall with cs.rpl != cs.dpl", test_count == 1); > +} > + > int main() > { > setup_vm(); > @@ -256,6 +278,7 @@ int main() > > test_kernel_mode_int(); > test_vm86_switch(); > + test_conforming_switch(); > > return report_summary(); > } > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Aug 19, 2014, at 4:28 PM, Paolo Bonzini <pbonzini@redhat.com> wrote: > Il 19/08/2014 15:04, Nadav Amit ha scritto: >> >> +void test_conforming_switch(void) >> +{ >> + /* test lcall with conforming segment, cs.dpl != cs.rpl */ >> + test_count = 0; >> + set_intr_task_gate(0, user_tss); > > No need to use set_intr_task_gate, since the IDT is not involved here. > > tss_intr.eip = (u32)user_tss; > > is enough. > > I fixed this up and applied the patch. Thanks! I know, but all the other ‘call' tests did. If there is an error, at least it should be consistent. ;-) Thanks, Nadav
diff --git a/x86/taskswitch2.c b/x86/taskswitch2.c index 92fc941..1fe833e 100644 --- a/x86/taskswitch2.c +++ b/x86/taskswitch2.c @@ -7,6 +7,7 @@ #define MAIN_TSS_SEL (FIRST_SPARE_SEL + 0) #define VM86_TSS_SEL (FIRST_SPARE_SEL + 8) +#define CONFORM_CS_SEL (FIRST_SPARE_SEL + 16) static volatile int test_count; static volatile unsigned int test_divider; @@ -102,6 +103,14 @@ start: goto start; } +static void user_tss(void) +{ +start: + test_count++; + asm volatile ("iret"); + goto start; +} + void test_kernel_mode_int() { unsigned int res; @@ -248,6 +257,19 @@ void test_vm86_switch(void) report("VM86", 1); } +void test_conforming_switch(void) +{ + /* test lcall with conforming segment, cs.dpl != cs.rpl */ + test_count = 0; + set_intr_task_gate(0, user_tss); + + tss_intr.cs = CONFORM_CS_SEL | 3; + tss_intr.ds = tss_intr.gs = tss_intr.fs = tss_intr.ss = USER_DS; + set_gdt_entry(CONFORM_CS_SEL, 0, 0xffffffff, 0x9f, 0xc0); + asm volatile("lcall $" xstr(TSS_INTR) ", $0xf4f4f4f4"); + report("lcall with cs.rpl != cs.dpl", test_count == 1); +} + int main() { setup_vm(); @@ -256,6 +278,7 @@ int main() test_kernel_mode_int(); test_vm86_switch(); + test_conforming_switch(); return report_summary(); }
Commit 5045b46803 added a check that cs.dpl equals cs.rpl during task-switch. This is a wrong check, and this patch introduces a test in which cs.dpl != cs.rpl. To do so, it configures tss.cs to be conforming with rpl=3 and dpl=0. Since the cpl after calling is 3, it does not make any prints in the callee. Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> --- x86/taskswitch2.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+)